The present invention relates to the field of surgical cutting instruments, and more specifically, to an instrument useful in cutting percutaneous sutures.
As with other surgical procedures, the task of suture removal has lead to a variety of instruments intended to make it both simpler and safer These instruments may generally be grouped into three categories. The first category consists of instruments having a single, unopposed knife blade. One using such an instrument inserts the blade between the skin and the suture, with the cutting edge of the blade engaging the suture. Then, a quick thrust away from the skin severs the suture material. The disadvantage of such instruments is that the pulling force transmitted by the suture from the knife to the skin, although slight, results in trauma to the surrounding tissue.
A second class of suture removal instruments utilizes scissors, i.e., a pair of blades which slide past each other, with the suture material being severed by the passing blades. These instruments do not transmit any significant tugging force to the skin, and thereby avoid any resultant trauma. On the other hand, they are manifestly more complex than a simple knife, and must be manufactured and maintained with a relatively high degree of precision in order to operate satisfactorily. Instruments of this type are disclosed in U.S. Pat. No. 4,246,698 to Lasner et al. and U.S. Pat. No. 3,541,684 to Beaver.
A third class of suture removal instrument has resulted from a desire to obtain the nontraumatizing advantages of scissors in an uncomplicated instrument not requiring a great deal of precision. These instruments seek to achieve this effect by opposing a single blade with a cutting block or anvil. These instruments might properly be called "choppers." Such instruments are shown, for example, in U.S. Pat. No. 3,659,343 to Straus. In such instruments, the anvil serves also as a probe to be inserted between the suture and skin. The cutting edge of the blade, disposed on another arm of the instrument, is then brought toward the anvil, thus capturing the suture between the cutting blade and the anvil and severing it. While such instruments are, in general, satisfactory for suture removal, they have been limited by the fact that the anvil also serves as a probe, which imposes design constraints compromising its operation as either. In other words, it has been necessary to dimension and configure the anvil/probe structure in a fashion which compromises both functions. It is therefore desirable to overcome this disadvantage by designing a suture cutter in which this compromise can be avoided.